Projectile in the form of a hollow tube, having internal elevations or recesses or combinations thereof, such that air flowing through sets the projectile in rotation

ABSTRACT

The invention describes a tubular projectile which is suitable for being fired in particular by bows or crossbows (such as bolts and arrows), but can also be fired from other shooting devices (for example firearms). The arrow is set in rotation about its longitudinal axis by the air passing through after being fired. The rotation is achieved by elevations or recesses applied to the inner surface, which are primarily designed in a linear manner and, by interaction with the air passing through, create a trajectory-stabilizing rotation of the rod or hollow tube. To this end, the arrow generally requires no or less fletching or other elements that stabilize the trajectory.

The invention referred to here as IARV arrow consists of a hollow tube and serves as a projectile, in particular for firing with bows and crossbows, but also for firearms. Instead of or as a supplement to fletching and other known solutions for the flight path stabilisation of projectiles, such as bolts and arrows, elevations or recesses are applied to the inner side, which have a spiral progression, for example, over one or more regions of the hollow tube.

Elevations or recesses deflect the air flowing through out of the direction flowing straight through in such a way that, according to the law of conservation of angular momentum, the IARV arrow itself is displaced in the opposite direction in rotation about its longitudinal axis. The elevations or recesses (hereinafter “measures”) can be implemented as individual elements (“nubs”) or as a continuous line or a line in sections in one or more partial regions of the hollow tube, which generally then have a spiral progression.

Elevations and recesses can have different heights or depths or vary these within the projectile.

The linear measures can be implemented in sections or with breaks in the progression or in the shape of multiple linear regions. Combinations of elevations and recesses, individual elements and linear measures or different heights or depths can increase the efficiency—for example, enable higher speeds, greater ranges or lower vibration behaviour of the IARV arrow.

When implemented linearly, the generally spiral progression can have varying coil distances, in order to generate, for example, optimised interactions for different flight phases with the air flowing through.

The projectile speed is thus at its highest when fired, but the natural rotation at its smallest. During the flight, the speed generally decreases, whereas the speed of rotation increases and possibly asymptomatically approaches a maximum. The measures can be adapted for these different boundary conditions in order to optimise certain flight properties over the whole flight.

A possibility would be to design a partial region of the measures with smaller coil distances and thus accelerate the initiation and increase of the rotation directly after firing, while other sections with bigger coil distances optimise the rotation for a target value for the later flight phases. The elevations or recesses can be applied over any regions of the projectile, e.g. only in the initial region or at the end, as well as combined with one another in order to maximise the efficiency and to obtain adjustment options for different firing devices, the specific implementations thereof or individual firing speeds.

The rotation is thus independently obtained without active components, such as a barrel or a drive, for example, stabilises the flight and, if necessary, lessens vibrations of the IARV arrow after firing.

Kinetic energy is transferred from the firing impulse to the rotation. The slower speed reduces the air resistance and, if necessary, increases the flying range. The rotation energy is released when a target is hit and optionally increases the entry depth.

The IARV arrow is, amongst other things, suitable for firing with bows, crossbows or slingshots, but can also be accelerated by means of compressed air or explosives and propellants.

The tip (the tube end in the direction of flight) can be supplemented with arrowheads, provided that these have an entry opening for air flowing through, or air is directed into the tube interior by other means. Other forms of the tip are also possible, which enable a greater penetration depth into a target due to the rotation of the IARV arrow. This can be obtained, for example, through a tube tapering, cutting or a saw-tooth-like rim on the arrowhead. The tip can lead to an improved flight path as functionally necessary by means of further or greater weight.

The end of the arrow (the rod end opposite the direction of travel) can facilitate the firing with a bow or a crossbow by means of an indentation, e.g. for a bowstring.

Additional fletchings or spiral elevations or recesses on the outer side, for example, provide possible optimisations of the flight properties.

PRIOR ART

Arrows have been known for thousands of years and have hardly been changed in terms of their basic principle since then. A rod-shaped projectile is mechanically accelerated by a firing device, for example a bow, a crossbow or a slingshot, and fired in a thereafter undriven flight path towards a target.

For the stabilisation and extension of the flight path, a fletching attached to the end opposite the flight path or comparable measures are often used.

These measures increase the air resistance and lead to a deflection and vibration of the projectile if the projectile grazes the firing device during the firing or positive acceleration phase. The accuracy and reproducibility of the flight path is strongly influenced by the aerodynamic properties of these measures and, in particular, by their ageing process and mechanical changes such as wear.

Fletchings or comparable measures also lead to an inefficient use of space for storage and transport (e.g. in a quiver) as well as greater expense during the production.

According to the patent specification DE000019638264C2, a bow is presented which directs arrows by means of a tube attached to the bow in such a way that said arrows are hereby set in rotation and their flight path is stabilised. Conversely, the invention presented here describes an arrow which independently causes the stabilising rotation without changes to the firing device.

According to the patent specification DE000008810059U1, an arrow is described which causes a rotation about the longitudinal axis by means of a specific design of the fletching. In contrast to this invention, in the case of the IARV arrow, no fletchings are necessary for the causation of the rotation.

According to the patent specification GB2385804 (A), a dart is described which is supposed to be prevented from jumping out of a dartboard. However, the dart is unchanged in relation to the flight stabilisation and thus does not anticipate the properties of this invention.

According to the patent specification GB0201183.1, an arrow is described which consists of a hollow tube, having an inner diameter which can vary across the length, in order to optimise the weight distribution and to increase the stability, in particular for striking a target. On one hand, this invention counts on material applied radially symmetrically and, on the other hand, does not relate to any technical properties which concern flight stabilisation, apart from the weight distribution. Thus it does not anticipate the properties of this invention.

Conversely, the present invention completely or extensively replaces the necessity for fletching or comparable measures and thereby avoids the above-cited problems for the production, firing, flight path, storage and transport. It allows the use of the invention without changes or special features on firing devices. A special adjustment of firing devices to this invention can, where applicable, increase the efficiency.

The invention further allows the simpler, more cost-effective and material-saving production of projectiles from one single material or fewer materials in fewer steps and can largely be automated. 

1. Hollow tube (“projectile”, “IARV arrow”) characterised in that, due to elevations and/or recesses on the inner side of the tube, a rotation movement after firing by means of a suitable device such as a bow or crossbow, for example, is obtained, strengthened, maintained or decelerated by means of a medium flowing through when moving.
 2. Projectile according to claim 1, characterised in that the elevations and/or recesses are implemented both as small elements (“nubs”) and in a linear design. In particular, this applies to spiral nub arrangements and/or lines of elevations and/or recesses. The elevations and recesses can vary in height or depth as well as in their distances, e.g. coil distances, as well as in the distribution across the inner wall of the hollow tube (“optimisation options”). Some of these optimisation options in different forms can arbitrarily combine with each other.
 3. Projectile according to claim 1, characterised in that the elevations and/or recesses are implemented in such a way that a desired rotation speed—asymptomatically approximated if necessary—is obtained or (e.g. unintended) rotation movements are avoided or decelerated.
 4. Projectile according to claim 1, characterised in that the front end in the direction of flight includes a diameter increase for better reception of the medium flowing through or additional openings (“inlet slits”) which serve the improved intake of the medium flowing through.
 5. Projectile according to claim 1, characterised in that a weight-increasing element is attached on the front end (in the direction of flight) or a heavy material is used. This can occur, for example, by the material strength being increased there or another heavy material or an additional coating or an interior, heavy ring also being used as ballasting if necessary.
 6. Projectile according to claim 1, characterised in that an element often implemented by an indentation for the reception of a string is attached on the back end (opposite the flight path).
 7. Projectile according to claim 1, characterised in that several projectiles are designed with different diameters in such a way that they can be fitted one into the other, in order to save space, for example.
 8. Projectile according to claim 1, characterised in that a tip, cutting edge or a taper, for example, is attached on the front end (in the direction of flight), which serves the purpose of a greater penetration depth, by minimising the target surface, or a cutting effect into a target independent of rotation.
 9. Projectile according to claim 1, characterised in that an element is attached to the front end (in the direction of travel), which causes a greater penetration depth or greater effect on the target due to the rotation. This can be, for example, a sawtooth design of the opening of the hollow tube which mills into the target, as it were, or a drill-like design of the tip.
 10. Projectile according to claim 1, characterised in that elements are attached to the projectile which cause an effect independent of impulse and rotation of the projectile, due to the additional properties. These could be, for example, explosive tips, harmful or poisonous substances, an intended splinter effect in the material or comparable measures. 